DE 199 28 915 A1 discloses a method by means of which the visual range in the field of view of a motor vehicle can be determined exactly, so that the driver can be caused to adapt his driving style with the aid of the visual range information. In this case, a monocular video sensor measures the contrast of an object which is detected by a radar or LIDAR sensor, and determines the visual range from the measurement values which are produced by the radar or LIDAR sensor and by the monocular video sensor. As an alternative to this, the distance to the at least one object and its contrast are measured by means of a binocular video sensor, and the visual range is then determined from the contrast and distance measurement values. Apart from the contrast measurement, no further evaluation is carried out on the image data recorded by the video sensor. Furthermore, it has been found to be disadvantageous that the LIDAR sensors which are suitable for relatively large measurement ranges lose position resolution as the distance to an object increases, thus resulting in a deterioration in the object identification.